Research shows that people are not good at making these sorts of decisions (Kahneman and Tversky won the Nobel Prize in Economics for it). History shows us the same thing. We don't "think" people aren't "smart" enough to make informed decisions - we KNOW the way human's brains work makes it HARDER for us to make SMART decisions even when we are informed. FFS people bought the whole supply side economics/Laffer curve when the most cursory analysis combined with some psychological knowledge shows that both fall apart very quickly. Look up judgment under heuristics or judgment under uncertainty. Even highly intelligent and highly educated people make terrible decisions, especially when it comes to money. And bankers KNOW this stuff. They KNOW people aren't good at making decisions like this and they propagandize their sales language in a way that makes it even harder for people to make these types of decisions.
Not all people have the level of privilege you have to allow yourself to take the risk of a longer loan and pay it off earlier. 50 year mortgages would double the amount of interest people would pay for the house to save a few hundred dollars. It is yet another way to transfer wealth from the poor and working class to bankers and the wealthy. It is a predatory practice pushed under the guise of "options." It is a form of usury in sense that it makes a loan that unfairly enriches the lender.
There are better ways to provide more choices for homeowners than allowing bankers to prey on them even more! How about we pay people enough money to be able to afford to buy a house?